1. Field of the Invention
The present invention relates to an engine in which various cylinder valves are operated by more than one type of actuation device.
2. Disclosure Information
Engine designers seeking to increase automotive powerplant fuel economy and performance, while decreasing engine emissions, have explored the concept of variable valve timing for a considerable period of time. Although attempted from time to time, electronically driven valves, such as solenoid operated valves, have not generally been successful because the amount of power required to open a valve to an extent necessary to allow air charge to enter an engine's cylinder during operation at maximum power was considerable and impaired fuel efficiency of the engine. This is particularly true where electronic has been applied to an exhaust valves, which must open when the cylinder is under positive pressure. The present invention allows the use of a randomly operable, electronically powered intake valve in combination with a selectively operable camshaft-powered intake valve and a conventionally powered camshaft driven exhaust valve. This inventive valve arrangement, while allowing the flexibility of electronically controlled valves, permits such flexibility along with greatly reduced power consumption.